24 Sep “One of the things that happens as you fall asleep is your muscles relax, but the awake part may still be stimulating enough that it will temporarily overreact and you get this jerk of muscle activity,” he says. And for reasons that are unclear, it's sometimes accompanied by an image. Sleep starts are usually. Although these things have an anecdotal link, and it is true that people with bad sleep habits do suffer from them, they also occur at random in completely normal people who do get enough sleep. Another possible cause of the falling sensation that goes alongside hypnic jerks is the brain misunderstanding what is. 21 Nov The phenomenon, known as a hypnogogic jerk, is named in reference to the hypnogogic state — the transitional period between wakefulness and sleep. Hypnagogic jerks are also commonly known as hypnic jerks or sleep starts.